Preparation and characterization of bovine serum albumin surface-imprinted thermosensitive magnetic polymer microsphere and its application for protein recognition

A novel bovine serum albumin surface-imprinted thermosensitive magnetic composite microsphere was successfully prepared by the surface grafting copolymerization method in the presence of temperature-sensitive monomer N-isopropylacrylamide (NIPAM), functional monomer methacrylic acid (MAA) and cross-linking agent N,N'-methylenebisacrylamide (MBA). The structure and component of the thermosensitive magnetic molecularly imprinted microsphere were investigated by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), vibrating sample magnetometer (VSM) and thermogravimetric analysis (TGA). The results of thermosensitivity, adsorption capacity, selectivity and reusability showed the formation of a thermosensitivity grafting polymer layer P(NIPAM-MAA-MBA) on the surface of Fe₃O₄atSiO₂ and the good adsorption capacity and specific recognition for template protein. When the adsorption temperature was higher than the lower critical solution temperature (LCST) of poly(N-isopropylacrylamide) (PNIPAM), shape memory effect of imprinted cavities would be more effective. In other words, it was more conducive to capture template molecules under this condition and the imprinting factor would be higher. On the other hand, when the desorption temperature was lower than LCST of PNIPAM, the decrease of shape memory effect between imprinted cavities and template molecules would facilitate the release of template molecules from the imprinted cavities. Based on this property, the adsorption and desorption of template molecules could be regulated by system temperature indirectly which benefited from the existence of thermosensitivity imprinting layer.